N-substituted amide derivatives of 1, 1-dihydroperfluoroalkylamines



United States Patent N-SUBSTITUTED AMIDE DERIVATIVES or 1,I-DIHYDROPERFLUOROALKYLAMINES Donald R. Hus'te'd, St. Paul, and Arthur H. Ahlbrecht, White Bear'Township, Ramsey County, Minn., assignors to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware No Drawing. Application February 8, 1954, Serial No. 408,995

5 Claims. (Cl. 260561) This application is a continuation-in-part of our copending application S. N. 149,458, filed March 13, 1950; since issued as Patent No. 2,691,043 on Oct. 5, 1954.

This invention relates to a new and useful class of fluorocarbon compounds.

These new compounds are amides derived from fluorinated primary amines (that have in the molecule a fully fluorinated terminal fluorocarbon tail) by replacement of a nitrogen-bonded hydrogen atom with an acyl group. More particularly, they are N-substituted amide derivateives of 1,1-dihydroperfluoroalkylamines wherein the perfluoroalkyl group provides the molecule with a terminal fluorocarbon group (serving as a fluorocarbon tail) containing from 3 to 12 fully fluorinated carbon atoms. The parent 1,1-dihydroperfluoroalkylaminc compounds are described and claimed in our aforesaid prior application, and have the formula:

where n has an integer value of 3 to 12.

The present amide derivative compounds may be termed N (1,1 dihydroperfluoroalkyl)acylamides and are represented by the formula:

where n has an integer value of 3 to 12, and RC0 is an aliphatic acyl group (i. e., the residue of an aliphatic monocarboxyli'c acid, the hydroxyl group of which has been replaced); R" representing the saturated or unsaturated terminal sub-group which is an alkyl group, a perfiuoroalkyl group, or an alkenyl roup, bonded to the carbonyl carbon atom, both hydrocarbon and fluorocarbon groups being illustrated by the experimental examples hereinafter described. The acyl group may contain a lengthy R chain, such as that of stearic acid (in which case the acyl group is a stearyl group, which contains 18 carbon atoms).

In the actual preparation of these compounds the acyl group is not supplied by employing a free acid (the use of which would result in a salt rather than an amide) but by using an acid chloride or an acid anhydride. Use can also be made of esters although in general they are not as satisfactory. The reaction is performed under anhydrous conditions. The reactions in which an acid chloride or an acid anhydride is reacted with the amine to produce the desired amide product are shown by the respective equations:

CnFan-g-1CH2NH2+ (RCO) 20-) RCONHCH2CnFzn+r+RCOOH These amide compound are highly resistant to hydrolysis by acid and base. For this reason the standard Kjeldahl analytical procedure is ineffective. Several of the amides distilled unchanged from refluxing in concentrated sulfuric acid during attempts to analyze them by this method.

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The saturated compounds are extremely stable and are highly resistant to oxidation. Their solubility properties depend in part upon the terminal groups. When both are relatively short, these compounds are only slightly soluble in water, and they become increasingly insoluble with increase in chain length. They are soluble in oxygenated organic solvents (such as acetone and ethers). The fluorocarbon tail supplied by the amine compound is per se both hydrophobic and eleophobio and becomes increasingly so with increase in length, and renders its end of the amide molecule insoluble in both aqueous and organic liquids. V When the fR .group is a methyl or other hydrocarbon alkyl group, the molecule has a terminal group that imparts solubility in oils and hydrocarbon liquids, and increasingly so as the length of the group increases to provide an oleophilic alkyl tail that strongly solubilizes that end of the molecule toward oils and hydrocarbon liquids, although it is hydrophobic and insolubilizes that end of the molecule toward water.

that is both hydrophobic and eleophobic, and a hydrocarbon tail at the other end that is hydrophobic but eleophilic; and such compounds have utility as surface active agents for uses where this combination is desirable (for example as an emulsifying agent for fluorocarbons and oils, the agent collecting at the interfaces with the fluorocarbon tails dissolved in the fluorocarbon phase and the hydrocarbon tails dissolved in the oil phase). When the acyl group provides a fluorocarbon R group tail (as in the case of the acyl group of perfluorobutyric acid), then both ends of the amide molecule have fluorocarbon tails and such compounds are relatively insoluble both in water and in oils but are soluble in fluorocarbon liquids.

The saturated amides, because of their extreme thermal stability and because they are low-melting and highboiling, have utility as heat exchange liquids for use at elevated temperatures. Most but not all of the compounds are solid at room temperature. However, the N-( l l-dihydroperfluorobutyl) butyr'amide:

CIiH'lCONHCHZCBF'I for example, is an oil at room temperature and has a vacuum boiling point of 107 C. (at 12 mm.), and is believed to have practical utility as'a pumping fluid for oil-diifusion type high-vacuum pumps.

Of particular interest are the amides containing unsaturated acyl groups in which R is an alkenyl group. These are highly stable to hydrolysis, but are reactive and provide starting compounds for making derivatives. They also have utility in providing reactive monomers from which various useful polymers and copolymers can be made, the acrylamide and methacrylamide compounds being particularly noteworthy. An example of a homopolymerizable monomer, that polymerizes inter se when heated in the presence of a little benzoyl peroxide catalyst, is the N-(1,l dihydroperfluorohexyl)acrylamide:

The following illustrative experimental examples provide further data on the subject compounds.

Example 1 This example illustrates the preparation of the normal N-( 1, 1 -dihydroperfiuorobutyl.) acetamide compound CHaCONHCHzCFzCFzCFa which is the lowest member of the series, containing the smallest number or carbon atoms. In this case the fluo rocarbon tail is a normal perfluorobutyl group contain- Thus it is possible to provide a molecule having a fluorocarbon (perfluoroalkyl) tail at one end ing three ,fully fluorinated carbon atoms. The formula can also be written as:

omo-fi-omohomcm which more clearly shows the structure.

A 25 ml. flask equipped with a reflux condenser was charged with 5 grams of normal.1,1-dihydroperfluorobutylamine: i 7

a liquid compound having a boiling point of 68 C. (at 740 111111.). To this was slowly added at room temperature 3.06 grams of acetic anhydride:

(CI-IsCOhO 'tively pure form. The melting point was 51.5 C. Analysisshowed 51.3% fluorine (calc. 55.2%) and 5.78%

: nitrogen (calc.'5.82% The infrared absorption spectral curve confirmed the identification.

, V ExampleZf V 7 The procedure was the same as in'the preceding example except that the flask was charged with 3.2 grams of the butylamine to which was added 6.2 grams of normal perfluorobutyric anhydride: 7

The crystalline product after washing twice with water and recrystallizing from hot carbon tetrachloride, was

' uum distillation to remove the ether.

identified as relatively pure normal N-( 1,1 dihydroperit had a melting point of 6364 C. Fluorine analysis showed 66.7% F (calc. 67.3%). On attempted analysis for nitrogen by the standard Kjeldahl procedure, the sample sublirned unchanged from hot sulfuric acid. The infrared curve substantiated the identification.

Example 3 The apparatus was a 100 ml. 3-necked flask fitted with a reflux condenser Whose outlet was protected by a drying tube, a magnetic bottom-drive stirrer, and a dropping funnel. It was charged with 9.95 grams (0.05 mole) of l,l-dihydroperfluorobutylarnine and 30 ml. of anhydrous diethylether. To.this;solution was added dropwise with vigorous stirring 2.67 grams (0.025 mole) of butyryl chloride. Stirring was continued at 25 C. for one hour after the addition to allow completion of the reaction. At the end of this time the white precipitate of 1,1-dihydroperfluorobutylamine hydrochloride (CzFvCHzNHz-HCl) wasremoved by filtration.

The filtrate was concentrated by vacuum distillation to remove the ether; The product (3.2 grams) was a viscous oil, having a boiling point of 107 C. at 12mm 'and was identified as N-(1,l-dihydroperfluorobutyl)bu tyramide: A p

' CH3CH2CH2CONHCH2CF2CF2CF3 The procedure was the same as in the preceding ex ample except that the 'butylamine (9.95 grams) was reacted with 7.6 grams (0.025 mole) of stearyl chloride (CnHasCOCl). After vacuum distillation, the crude waxy amide product was recovered in a yield of 12 grams and j had a melting point of 63.0-64.4 C. It was purified by sublimation in a high vacuum at 59 C. (10* mm. pressure) and then had a melting point of 65 .566.0 C. It was identified as relatively pure N-(1,1-dihydroperfluorobutyl stearamide:

Analysis showed 31% F (calc. 29%), and 3.23% N (calc. 3.01%). This compound can also be purified by recrystallization from a hot ethanol-water mixture. 7

Example 5 The apparatus was a ml. 3-necked flask equipped with a reflux condenser, magnetic stirrer, and dropping funnel. It was charged with 15.7 grams (0.05 mole) of normal 1,1-dihydoperfluorohexylamine and 35 ml. of anhydrous ether. To the solution was added with stirring 1.96 grams (0.025 mole) of acetyl chloride. Stirring was continued for 1 /2 hours after the addition was completed. The precipitated amine hydrochloride was removed by filtration and the filtrate was subjected to vac- The crude amide product had a melting point of 54.5. C. It was purified by vacuum sublimation .at 40 C. and 10 mm. pressure and then had a melting point of 53.0-53.5 C. It was identified as relatively ipure normal N-(1,l-dihydroperfluorohexyl acetamide;

CHsCONHCHzCsFn' Analysis showed 28.0% (calc. 28 .2%), 62.0% F (calc. 61.3%), and4.09% N (calc. 4.12% v a Q I Example "The procedure was the same as in the preceding'example except that the hexylamine (15.7 grams) was reacted with 5.82 grams (0.025 mole) of perfluorobutyryl chloride. 'The crude amide product (11 grams) had a melting point of 4950 C. It was purified by vacuum sublimation and then had a melting point of 49.5 50.0 C. 'It was identified as relatively pure normal N-(l,1-dihydroperfluorohexyl)perfluorobutyramide:

Analysis showed 24.2%. C (calc. 24.2%), 70% F (calc. 69% and 2.79% N (calc. 2.82%). The Debye-Scherrer X-ray fine powder pattern showed three prominent lines: 4.76 vvs, 4.53 vv's,'4.34 vs. T

Example 7 In the same manner the hexylamine (15.7 grams) was reacted with 2.66 grams 0.025 mole) of butyryl chloride. The purified amide product obtained by sublimation (at 38 C. and 10* mm. pressure) hada melting point of.

34.0-34.5 C. and was identified as relatively pure normal N-( 1 1-dihydroperfluorohexyl)butyramide:

CaHvCONHCHzCsFn Analysis showed 3.74% N (calc. 3.79%

' Example 8 V fluorohexyl) stearamide:

CnHasCCNHCHzCsFn Analysis showed 2.52% N (calc. 2.47%).

The following examples illustrate the preparation of acrylamide derivatives, which are reactive and capable of polymerization, and have the general formula:

CH2=CHCONHCH2QtF2n+1 where n has an integer value of 3 to 12.

Example 9 The apparatus was a 100 ml. 3-necked flask equipped with a reflux condenser protected by a drying tube outlet, a magnetic bottom-drive stirrer, and a dropping funnel. It was charged with 9.95 grams (0.05 mole) of 1,1-dihydroperfluorobutylamine and 30 ml. of anhydrous ether. To this solution was added dropwise with vigorous stirring 2.25 grams (0.025 mole) of acrylyl chloride (CH2=CHCOCl). Stirring was continued at 25 C. for one hour to allow completion of the reaction. The precipitated amine hydrochloride (CsFqCHzNI-Iz-HCI) was removed by filtration and amounted to 5.6 grams.

The filtrate was subjected to vacuum distillation to remove the ether and provide 6.3 grams of crude amide product. This was purified by recrystallization from petroleum ether (B. P. 30-60 C.) and resulted in a product having a melting point of 57.2-57.4 C., which was identified as relatively pure normal N-(1,1-dihydroperfluorobutyl) acrylamide:

Analysis showed 33.6% C (calc. 33.2%), 54.0% F (cal. 52.5%), and 5.46% N (calc. 5.53%). The infrared absorption spectral curve showed absorption bands characteristic of CF, CH, C=C, amide C=O, and CNH. No starting material was identified as being present.

This compound was found to polymerize when heated in an evacuated ampoule with a small amount of benzoyl peroxide catalyst.

Example The apparatus was a 500 ml. 3-necked flask equipped with a reflux condenser protected by a drying tube outlet,'a magnetic stirrer, and a dropping funnel. It was charged with 90 grams (0.3 mole) of 1,1-dihydroperfluorohexylamine and 200 ml. of anhydrous ether. The flask was cooled in an ice bath. To the solution was added dropwise with constant stirring 13.5 grams (0.15 mole) of acrylyl chloride. Then 50 m1. of ether was added and stirring was continued for 3 hours. The white precipitate of amine hydrochloride was removed by filtration and amounted to 50.1 grams.

The filtrate was subjected to vacuum distillation to remove the ether, and the crude product was purified by recrystallization from a mixture of petroleum ether and diethyl ether in 6 to 1 ratio, heating to eflect solution and then cooling in an ice bath with stirring. The crystals were recovered by filtration and air dried. Yield was 46.5 grams (88% This purified product had a melting point of 63-64 C. and was identified as relatively pure normal N-(1,1-dihydroperfluorohexyl) acrylamide:

Analysis showed 3.98% nitrogen (calc. 3.97%).

A sample of this acrylamide was heated in an evacuated glass ampoule for 90 minutes at 170 C., using 0.1% benzoyl peroxide as catalyst. The homopolymer product was a light tan, transparent, brittle solid. It began to soften on a heated brass block at 115-130 C. and be came fluid with some discoloration at 240 C. It was soluble in methyl perfluorobutyrate, but was insoluble in water and in hydrocarbons and common organic solvents. The surface of the polymer was both hydrophobic and oleophobic. Transparent films could be formed by casting solutions of the polymer in methyl perfluorobutyrate. Transparent fibers could be drawn both from these solutions and from the molten polymer. A solution of this polymer in methyl perfluorobutyrate had an inherent viscosity of 0.27 at a concentration of 0.66 gram per 100 m1. of solution.

Copolymerization is illustrated by experiments in which samples of this acrylamide monomer were mixed with equimolar portions of each of the following comonomers: styrene, acrylonitrile and vinyl acetate, and sealed in evacuated glass ampoules with 0.1% benzoyl peroxide as catalyst. The ampoules were heated for 18 hours at -98 C. The styrene copolymer was a white, translucent, crumbly resin which softened on a heated brass block at C.; it was soluble in methyl perfluorobutyrate. The acrylonitrile copolymer was a hard, brittle, transparent yellow resin which softened on a heated brass block at C. It was insoluble in common organic solvents. The vinyl acetate copolymer was a hard, colorless, transparent resin which softened on a heated brass block at 100 C. and was slightly soluble in methyl perfluorobutyrate.

Example 11 The apparatus was a 50 ml. flask equipped with reflux condenser, magnetic stirrer, and dropping funnel. It was charged with 4.0 grams (0.01 mole) of normal 1,1-dihydroperfiuorooctylamine and 15 ml. of anhydrous ether. To this was added dropwise with constant stirring (and with the flask cooled in an ice bath) 0.45 gram (0.005 mole) of acrylyl chloride. After further stirring for 2 hours, the white solid amine hydrochloride precipitate was removed by filtration.

The crude amide product (recovered by vacuum distillation of the filtrate to remove the ether) had a melting point of 49-50 C. It was purified by vacuum sublimation at 40 C. and 10 mm. pressure. The product had a melting point of 49-50 C. and was identified as relatively pure normal N-(1,1-dihydroperfluorooctyl)acrylamide:

Analysis showed 63% F (calc. 63%) and 3.06% N (calc. 3.04%).

We claim:

1. As new and useful compounds, the N-(1,1-dihydroperfiuoroalkyl)acylamides having the formula:

where RC0 is an aliphatic acyl group in which R is a terminal sub-group of the class consisting of alkyl, perfluoroalkyl and alkenyl groups, and n has an integer value of 3 to 12.

2. The compound N-( 1,1-dihydroperfluorobutyl) perfluorobutyramide having the formula:

3. The compound N(1,l-dihydroperfluorobutyl)butyramide having the formula:

CHsCHzCHzCONHCHzCFaCFzCFs 4. The compound N-(1,l-dihydroperfluorobutyl)acetamide having the formula:

CHaCONI-ICHaCFzCFzCFa 5. The compound N-( 1,1-dihydroperfluorohexyl)a rylamide having the formula:

References Cited in the file of this patent UNITED STATES PATENTS 2,521,902 Coover et al. Sept. 12, 1950 2,559,752 Berry July 10, 1951 2,617,817 Ahlbrecht Nov. 11, 1952 OTHER REFERENCES Bourne et al.: J. Chem. Soc. (London), Oct. 1952, pp. 4014-19. 

1. AS NEW AND USEFUL COMPOUNDS, THE N-(1,1-DIHYDROPERFLUOROALKYL) ACYLAMIDES HAVING THE FORMULA: 